"Building a label printer using Python, Arduino, duct tape and paperclips" by Johan Beyers

A Lightning Talk at PyCon ZA 2020

Transcript

1. Building a label printer using Python, Arduino, duct tape and paperclips. And: • Hot glue • Cable ties • A washing peg • A ruler • A hobby servo • Skateboard bearings • Polymorph (the plastic, not the company) • Sandpaper • A pencil • A Coke can • A series of tubes • Plus various cannibalised bits from my garage
2. Hackathon • Half a weekend • Build something useful • Or not • One step at a time • TLAR design methodology I had an idea….
3. The physical build Masking tape roll on a threaded rod, turning slowly. One rotation moves it 1mm sideways (spiral). Detect a starting point (Coke can, paperclips). Raise/lower a pen to create pixels.
4. Software Laptop running a Python script: • Convert text to image • Convert image to list of lists of colour values • Send timed up/down commands to Arduino Arduino is just a dumb controller: • Drive the motor • Send a start position trigger to the laptop • Receive up/down and move the pen
5. Python: Getting the image
6. Python: Control
7. Results: • 11 hours zero to Hello World • 48 lines of Python code • 68 lines of Arduino code • 0 test coverage • 40 labels printed to date • 8 minutes per label • 1 lightning talk Definitely worth it, would do again.
8. http:/ /johan.beyers.co.za Talk to me about: • Python • Takealot (We’re hiring!) • Maker evenings (on hold) Or some other projects: • 3D printer • Dog speedometer • Simple drawing machine • Perpetual Pendulum Wave • Electric bicycle